Battery powered electrical and electronic devices have the advantage of portability. However, when the battery supplying electrical power requires replacing the device usually becomes inoperable during removal of the battery and insertion of a replacement battery. This can be inconvenient, for example, if the device is a mobile phone or pager as the replacement of a battery may result in a premature termination of an important business transaction or loss of a paged message.
To overcome the above problem, temporary storage elements such as switched capacitors have been inserted into the power backup circuitry of portable electronic devices. These capacitors have an associated switch which, upon the removal of the battery, will automatically connect the capacitor to the electronic circuitry of the device. The replacement battery can then be inserted without the device becoming inoperable by the temporary loss of power. However, the switched capacitors or other similar storage elements can increase the cost and size of the portable device which is undesirable especially for portable devices such as pagers and mobile phones.